Question

#dataframe a, b:
a = [1,2,3,7,2,6,4]
b = [[0.7, 1.5],[1.6, 2.9],[3, 4.7],[4.8, 8]]
# b[k][0] <= a[i] <= b[k][1]
#I need to create a dataframe like:
c = [[0.7,1,1.5],[1.6, 2,2.9],[3,3,4.7],[4.8,7,8],[1.6,2,2.9],[4.8,6,8],[3,4,4.7]];

条件：添加两个新列，我不能使用循环

Answer 1

使用列表理解：

print([[x, y, z] for y, (x, z) in zip(a, b)])

输出：

[[0.7, 1, 1.5], [1.6, 2, 2.9], [3, 3, 4.7], [4.8, 7, 8]]

Answer 2

看到输入数据，我将假定此前提条件（OP提到了其中的一部分）：

对于所有k，k      b [k] [0] <= b [k] [1]

对于所有k，k      b [k] [1] <= b [k + 1] [0]

对于任何i，i      存在这样的i，k：
     b [k] [0] <= a [i] <= b [k] [1]

使用递归：

def rec_a(a: list, i: int, b: list):
    if i >= len(a):
        return []
    else:
        # Put result of rb in a list in order to extend it
        rb = [rec_b(a[i], b, 0)]
        # Get rest of the result
        ra = rec_a(a, i+1, b)
        # Merge the rest of the result with the current one
        rb.extend(ra)
        return rb

def rec_b(elem: float, b: list, k: int):
    if k >= len(b):
        return None
    elif b[k][0] <= elem <= b[k][1]:
        return [b[k][0], elem, b[k][1]]
    else:
        return rec_b(elem, b, k+1)

def rec(a: list, b: list):
    """
    PRECONDITION:
        For all k, k < len(b):
        b[k][0] <= b[k][1]

        and for all k, k < len(b) - 1:
        b[k][1] <= b[k+1][0]

        and for any i, k that i < len(a) and k < len(b):
        exists such i, k that:
        b[k][0] <= a[i] <= b[k][1] 
    """
    return rec_a(a, 0, b)

运行

A = [1,2,3,7,2,6,4]
B = [[0.7, 1.5],[1.6, 2.9],[3, 4.7],[4.8, 8]]

print(rec(A, B))

意见：

[[0.7, 1, 1.5], [1.6, 2, 2.9], [3, 3, 4.7], [4.8, 7, 8], [1.6, 2, 2.9], [4.8, 6, 8], [3, 4, 4.7]]

如何基于此数据帧中的一列和另一列中的两列添加两列？

2 个答案: